JP2001354125A - Travel safety device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vehicle behavior from becoming unstable by unbalance of braking force of left and right wheels when performing automatic braking for avoiding contact with a front obstacle. SOLUTION: When the automatic braking is operated this time for the first time in a Step S6 since there is the possibility that one's own car contacts with an object in a Step S3, target brake pressure PB of the automatic braking is set to an initial value P0 in a Step S7, and the automatic braking is started. When detecting a slip of the wheels by the automatic braking in a Step S8 after starting the automatic braking in target brake pressure PB=P0, the target brake pressure PB of the automatic braking is reduced to P1 from the initial value P0 in a Step S9. Thus, the slip of the wheels is restrained, a braking force difference between the left and right wheels is reduced, and the vehicle behavior can be prevented from becoming unstable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device for detecting an object by means of an object detecting means such as a radar device and for avoiding the contact when it is estimated that the vehicle may come into contact with the object. The present invention relates to a driving safety device for a vehicle that automatically operates a vehicle.

[0002]

2. Description of the Related Art A radar device detects a relative distance and a relative speed of a forward obstacle such as a preceding vehicle, and when there is a possibility that the own vehicle may come into contact with the forward obstacle, an automatic braking device is operated to move forward. A traveling safety device for a vehicle that avoids contact with an obstacle or minimizes damage when contact occurs is known, for example, from Japanese Patent Application Laid-Open No. H11-227582.

[0003]

By the way, when a vehicle equipped with such a driving safety device performs automatic braking in order to avoid contact with an obstacle in front of the vehicle, right and left on a road surface having a friction coefficient partially different. If one of the wheels slips, there is a possibility that the braking forces of the left and right wheels become non-uniform and the vehicle behavior becomes unstable.

The present invention has been made in view of the above-mentioned circumstances, and when performing automatic braking to avoid contact with an obstacle ahead, unstable vehicle behavior due to imbalance of the braking forces of the left and right wheels. The purpose is to prevent the conversion.

[0005]

According to the first aspect of the present invention, there is provided an object detecting means for detecting an object in a traveling direction of an own vehicle, and an object detecting means for detecting an object in the own vehicle. Contact possibility estimating means for estimating the possibility of contact with the object detected by the control means, and braking control means for automatically operating the braking device when the possibility of contact is estimated by the contact possibility estimating means; And a braking force for reducing a target braking force of the brake control means when the slip detection means detects a slip at the time of braking by the brake control means. A traveling safety device for a vehicle, comprising a correcting means, is proposed.

According to the above construction, when a slip is detected by the slip detecting means during braking by the braking control means, the braking force correcting means reduces the target braking force of the braking control means, thereby suppressing wheel slip. It is possible to prevent the vehicle behavior from becoming unstable by reducing the braking force difference between the left and right wheels.

According to the second aspect of the present invention,
In addition to the configuration of the first aspect, the slip detecting means detects a slip based on the rotational speed of the wheel, and the braking force correcting means corrects the target braking force so that the slip amount of the wheel becomes equal to or less than a predetermined value. A driving safety device for a vehicle is proposed.

According to the above construction, the target braking force is corrected so that the slip amount detected based on the rotation speed of the wheel becomes equal to or less than the predetermined value. The power difference can be effectively reduced.

According to the third aspect of the present invention,
In addition to the configuration according to claim 1 or 2, there is provided a braking force estimating means for estimating an actual braking force at the time of braking by the braking control means, wherein the braking force estimating means estimates when the slip detecting means detects a slip. A driving safety device for a vehicle is proposed, wherein the braking force correcting means corrects the target braking force based on the braking force obtained.

According to the above configuration, the actual braking force when the wheel slips is estimated, and the target braking force is corrected based on the estimated braking force. It is possible to control the slip to the wheel by controlling the value to the optimum value according to the value, and to effectively reduce the difference in the braking force between the left and right wheels.

According to the invention described in claim 4,
In addition to the configuration according to claim 1 or 2, the vehicle control apparatus further includes a vehicle body deceleration estimating means for estimating a vehicle deceleration at the time of braking by the braking control means. A vehicle driving safety device is proposed in which the braking force correcting means corrects the target braking force based on the estimated vehicle deceleration.

According to the above configuration, the vehicle deceleration when the wheel slips is estimated, and the target braking force is corrected based on the estimated vehicle deceleration. It is possible to control the slip to the wheel by controlling the value to the optimum value according to the value, and to effectively reduce the difference in the braking force between the left and right wheels.

According to the invention described in claim 5,
In addition to the configuration according to any one of claims 1 to 4, further comprising an ABS control means for preventing the rotation of the wheels from being locked, and when the ABS control means operates during braking by the brake control means, the braking force is corrected. A vehicle driving safety device is proposed in which the means corrects the target braking force of the braking control means based on the braking force by the ABS control means.

According to the above configuration, since the target braking force is corrected based on the braking force by the ABS control means, it is possible to reduce the difference in the braking force between the left and right wheels while more appropriately suppressing the slip of the wheels.

According to the invention described in claim 6,
In addition to the configuration according to any one of claims 1 to 5, when the braking force difference between the left and right wheels is detected during braking by the braking control means, the braking force correction means decreases the target braking force of the braking control means. A driving safety device for a vehicle, characterized in that the driving safety device is provided.

According to the above configuration, the target braking force is reduced when the difference in braking force between the left and right wheels is detected, so that the difference in braking force can be accurately reduced.

According to the invention described in claim 7,
In addition to the configuration according to any one of claims 1 to 6, when a braking force difference between the left and right wheels is detected during braking by the braking control means, the braking force correction means performs braking based on the detected braking force difference. A traveling safety device for a vehicle is proposed which corrects a target braking force of a control means.

According to the above configuration, when a difference in braking force between the left and right wheels is detected, the target braking force is reduced based on the difference in braking force, so that the difference in braking force can be reduced more accurately. .

The target brake pressure PB of the embodiment corresponds to the target braking force of the present invention, and the radar device Sa of the embodiment corresponds to the object detecting means of the present invention.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 5 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving safety device, FIG. 2 is a block diagram of a braking system, and FIG. FIG. 4 is a block diagram showing the circuit configuration of the unit, FIG. 4 is a flowchart for explaining the operation, and FIG. 5 is a map for searching for the possibility of contact from the relative speed and relative distance.

As shown in FIGS. 1 and 2, a four-wheeled vehicle equipped with the traveling safety device of the present invention has left and right front wheels WFL, which are driving wheels to which the driving force of an engine E is transmitted via a transmission T. The vehicle includes a WFR and left and right rear wheels WRL and WRR, which are driven wheels that rotate as the vehicle travels. A brake pedal 1 operated by a driver is connected to a master cylinder 3 via an electronically controlled negative pressure booster 2. The electronic control negative pressure booster 2 includes a brake pedal 1
Is mechanically boosted to actuate the master cylinder 3, and the master cylinder 3 is actuated by a braking command signal from the electronic control unit U without automatic operation of the brake pedal 1 during automatic braking. When a depression force is input to the brake pedal 1 and a braking command signal is input from the electronic control unit U, the electronic control negative pressure booster 2 outputs the brake pressure having a predetermined value by taking the sum of the two.
The input rod of the electronic control negative pressure booster 2 is connected to the brake pedal 1 via a lost motion mechanism, and the electronic control negative pressure booster 2 is operated by a signal from the electronic control unit U to move the input rod forward. , The brake pedal 1 remains at the initial position.

A pair of output ports 7 of the master cylinder 3
Reference numeral 8 is connected via a hydraulic control device 4 to brake calipers 5FL, 5FR, 5RL, 5RR provided on the front wheels WFL, WFR and the rear wheels WRL, WRR, respectively. The hydraulic control device 4 includes four brake calipers 5FL and 5F.
R, 5RL, 5RR, four pressure regulators 6 are provided, and each pressure regulator 6 is connected to the electronic control unit U to be connected to the front wheels WFL, WFR and the rear wheels WR.
B, brake calipers 5FL, 5F provided on L, WRR
The operations of R, 5RL, and 5RR are individually controlled. Therefore,
Each of the brake calipers 5FL, 5
If the brake pressures transmitted to FR, 5RL, and 5RR are independently controlled, anti-lock brake control for suppressing wheel lock during braking can be performed.

The electronic control unit U transmits an electromagnetic wave such as a laser beam or a millimeter wave toward the front of the vehicle body, and based on the reflected wave, a relative distance ΔL and a relative speed ΔV between an object such as a preceding vehicle and the own vehicle. Device Sa for detecting the front wheel and the front wheel WF
L, WFR and wheel speeds of the rear wheels WRL, WRR, that is, wheel speed sensors Sb for detecting the wheel speeds Vw of the respective wheels.
And a yaw rate sensor S for detecting a yaw rate Y of the vehicle
c is connected. Instead of the radar device Sa, any means capable of detecting the relative distance ΔL and the relative velocity ΔV of the object, such as an image sensor using binocular vision, can be adopted.

The electronic control unit U controls the electronic control negative pressure booster 2 and the hydraulic control device 4 on the basis of the signal from the radar device Sa and the signals from the sensors Sb and Sc constituting the object detecting means of the present invention. In addition to controlling the operation, it controls the operation of the alarm device 10 including a buzzer, speaker, chime, lamp, head-up display, and the like.

As shown in FIG. 3, the electronic control unit U includes contact possibility estimating means M1, braking control means M2,
Slip detecting means M3, braking force correcting means M4, braking force estimating means M5, vehicle body deceleration estimating means M5 ', AB
S control means M6 is provided.

The contact possibility estimating means M1 estimates the contact possibility between the own vehicle and the object based on the relative distance ΔL and the relative speed ΔV between the own vehicle and the object detected by the radar device Sa. When the contact possibility estimating means M1 estimates that there is a possibility that the vehicle and the object will come into contact with each other, the alarm device 10 prompts the driver to avoid voluntary contact by voice or image, and the braking control means M2 performs the electronic control negative operation. The pressure booster 2 is operated to generate a brake pressure in the master cylinder 3, and the brake pressure is applied to the brake caliper 5 F via the hydraulic control device 4.
L, 5FR, 5RL, and 5RR to perform automatic braking.

The slip detecting means M3 includes left and right front wheels WFL, WFR and left and right rear wheels WR generated during braking.
Slip (skid) of the road surface of L, WRR is detected. Specifically, the vehicle speed Vv is calculated from the average value of the wheel speeds Vw output from the four wheel speed sensors Sb.
The slip ratio of each wheel is calculated by (Vv-Vw) / Vv. The braking force correcting means M4 corrects the braking force by the braking control means M2 based on the slip ratio detected by the slip detecting means M3 in order to prevent the vehicle behavior from becoming unstable due to the slip.

The braking force estimating means M5 and the vehicle body deceleration estimating means M5 'are used in the third and fourth embodiments which will be described later, and the braking force estimating means M5 is controlled by the braking control means M2. Is estimated on the basis of the output of the wheel speed sensors Sb..., And the vehicle deceleration estimating means M5 'calculates the actual deceleration of the vehicle occurring at the initial stage of braking by the braking control means M2. Wheel speed sensor S
Estimated based on the output of b ... The ABS control means M6 which activates the hydraulic control device 4 when a wheel slip is detected and reduces the braking force of the wheels to suppress the occurrence of locking is used in the fifth to seventh embodiments to be described later. It is used in. The braking force correcting means M4 is controlled by the braking control means M2 based on the output of the braking force estimating means M5, the vehicle body deceleration estimating means M5 'or the ABS control means M6 to prevent the vehicle behavior from becoming unstable due to slip. Modify power.

Next, the operation of the first embodiment will be described with reference to the flowchart of FIG.

First, in step S1, a relative distance ΔL and a relative speed ΔV of an object serving as an obstacle are detected based on the output of the radar device Sa, and in step S2, a wheel speed sensor S is detected.
b, front wheels WFL, WFR and rear wheels WRL, WR
The wheel speed Vw of R is detected and the yaw rate Y of the vehicle is detected by the yaw rate sensor Sc. In the following step S3, the possibility of the vehicle coming into contact with the object is estimated by the contact possibility estimation means M1 based on a search of the map shown in FIG. In this map, the horizontal axis represents the relative speed ΔV, and the vertical axis represents the relative distance ΔL. If the relative distance ΔL and the relative velocity ΔV are in an area below the threshold line, it is estimated that there is a possibility of contact, and the threshold line It is estimated that there is no possibility of contact if it is in the upper area of. When estimating the possibility of contact, if the vehicle speed Vv or the positive acceleration of the own vehicle is large, it is difficult to avoid contact by braking or contact by steering operation. Vehicle speed Vv
If the correction is made on the basis of the magnitude of the acceleration and the magnitude of the acceleration calculated by differentiating the vehicle speed Vv with time, a more accurate estimation can be performed. Further, the amount of overlap between the vehicle and the object in the left-right direction detected by the radar device Sa, the yaw rate sensor S
It is also possible to consider the turning state of the own vehicle detected in c.

If it is estimated in step S3 that there is no possibility of contact, the target brake pressure PB transmitted from the hydraulic control device 4 to the brake calipers 5FL, 5FR, 5RL, 5RR is set to 0 in step S4, and step S5 is performed. Then, the braking control means M2 executes automatic braking based on the target brake pressure PB (= 0). Therefore, when it is estimated that there is no possibility of contact, the automatic braking is not substantially executed.

If it is estimated in step S3 that there is a possibility of contact, and if the previous automatic braking is not activated in step S6, that is, if automatic braking is performed for the first time this time, the target brake pressure PB is set to an initial value in step S7. A certain P0 (for example, 6 MPa) is set, and in step S5, automatic braking is started based on the target brake pressure P0. In the next loop, the answer to step S6 is NO and step S8
When the slip detecting means M3 detects slip of any of the wheels in step S8, the braking force correcting means M4 sets the target brake pressure PB to P1 (for example, 4 MPa) smaller than the initial value P0 in step S9. The target brake pressure PB is kept at the initial value P0 if the slip is not detected by the slip detecting means M3 in step S8. As a result of executing automatic braking in this way,
If there is no possibility of contact in step S3, step S4
To set the target brake pressure PB to 0 to substantially end the automatic braking.

In general, when no slip occurs, the braking force of each wheel is substantially equal. However, when any wheel slips, the braking force of the slipped wheel is significantly higher than the braking force of the other wheels. Since the distance becomes smaller, there is a possibility that a difference in braking force between the left and right wheels occurs, and the vehicle behavior becomes unstable. However, as in the first embodiment, when slippage of any one of the wheels is detected, the grip force (braking force) of the slipped wheel is recovered by reducing the target brake pressure PB of all the wheels, and the slippage is reduced. Since the braking force of the wheels that are not running decreases, the difference in braking force between the left and right wheels can be reduced, and the vehicle behavior can be stabilized.

Next, a second embodiment of the present invention will be described with reference to FIG.

Steps S1 to S7 of the second embodiment
Is the same as that of the first embodiment described above. However, if there is no possibility of contact, the target brake pressure P
Every time B is set to 0, the subtraction type timer t is reset to 0 in the following step S11.

If there is a possibility of contact in step S3 and if the previous automatic braking is not activated in step S6, the target brake pressure PB is set to an initial value P0 (for example, 6 MPa) in step S7. Timer t in S12
Is reset to 0, automatic braking is started in step S5 based on the target brake pressure PB = P0. In the next loop, since the answer in step S6 is NO and the answer in step S13 is YES, the process proceeds to step S14. If the maximum value of the slip ratio of the four wheels is equal to or more than 10% in step S14, the target brake pressure PB is decreased from the initial value P0 by a predetermined value dP1 in step S15, and the timer t is set to the first value in step S16.
It is set to a set time T1 (for example, 0.5 sec).
In the next loop, since the answer in step S13 is NO, in step S17, the timer t is reduced by a predetermined value Tloop (for example, 10 msec) corresponding to the loop time. Therefore, in the automatic braking at the target brake pressure PB = P0−dP1, 0.5 seconds have elapsed and step S13 is performed.
And continues until the timer t times out.

When the timer t has timed out in step S13 and the slip ratio of any of the wheels is still 10% or more in step S14, the previous target brake pressure PB = P0-dP1 is further reduced by dP1. Automatic braking is continued at the new target brake pressure PB = P0-2dP1 until the first set time T1 of the timer t elapses. As described above, while the slip ratio of any of the wheels is 10% or more, the automatic braking is continued while the target brake pressure B is decreased by dP1 each time the first set time T1 elapses. Note that the minimum value of the target brake pressure PB in this case is Pm
in (for example, 2 MPa).

If the maximum values of the slip rates of the four wheels are less than 2% in steps S14 and S18, step S
At step S19, the current target brake pressure PB is increased by a predetermined value dP2, and at step S20, the timer t is set to the second value.
It is set to a set time T2 (for example, 0.1 sec).
Then, while the maximum value of the slip ratio of the four wheels is less than 2%, the automatic braking is continued while increasing the target brake pressure PB by a predetermined value dP2 at every second set time T2. still,
In this case, the maximum value of the target brake pressure PB is limited to Pmax (for example, the initial value P0 = 6 MPa). Thus,
As a result of reducing the target brake pressure PB over the first predetermined time T1 or increasing the target brake pressure PB over the second predetermined time T2, the maximum values of the slip rates of the four wheels are determined in steps S14 and S18. If it becomes less than 10% and becomes 2% or more, the automatic braking is continued while maintaining the target brake pressure PB at that time.

According to the second embodiment, when the slip ratio of any one of the wheels becomes 10% or more, the braking force difference between the left and right wheels is reduced by reducing the target brake pressure PB of all the wheels. Therefore, the vehicle behavior can be stabilized. In addition, by controlling the slip ratio of all the wheels in the range of 2% to 10%, the maximum braking force can be secured and the contact avoiding effect can be enhanced.

Next, a third embodiment of the present invention will be described with reference to FIGS.
An embodiment will be described.

Steps S1 to S8 of the third embodiment
Is substantially the same as that of the first embodiment described above, but in the third embodiment, in addition to detecting the wheel speed Vw and the yaw rate Y in step S2, the braking force estimating means M
5 estimates the actual brake pressure. That is, since the actual brake pressure does not always coincide with the target brake pressure PB due to the responsiveness of the actuator of the braking system or the like, as shown in FIG. Estimate in consideration of such factors.

When the slip of any one of the wheels is detected for the first time in step S21 after the start of the automatic braking, the flow proceeds to step S21.
At 22, the target brake pressure PB is searched by applying the estimated brake pressure at that time to the map of FIG. As is apparent from FIG. 9, the target brake pressure PB is set higher than the estimated brake pressure, and the estimated brake pressure is changed from 0 MPa to 4 MPa.
The target brake pressure PB is 2MPa while increasing to MPa.
From 6 to 6MPa and the estimated brake pressure is 4
When the pressure exceeds MPa, the target brake pressure PB is maintained at 6 MPa. That is, the target brake pressure PB is set so as not to exceed the estimated brake pressure by more than 2 MPa.

Since the estimated brake pressure immediately after a slip has occurred on any of the wheels can be considered to be substantially equal to the limit brake pressure of the wheel having the smallest limit braking force, the map is searched from the map shown in FIG. By performing automatic braking at the target brake pressure PB, it is possible to suppress the difference in braking force between the wheel on which the slip has occurred and the wheel on which the slip does not occur to a maximum of 2 MPa, so that the vehicle can be prevented from slipping due to the automatic braking. Behavior can be stabilized. This is because a slipping wheel generates only a braking force corresponding to the estimated brake pressure smaller by 2 MPa than the target brake pressure PB, and a non-slip wheel generates a braking force corresponding to the target brake pressure PB itself. This is because the difference in braking force between the two wheels can be suppressed to the maximum value corresponding to 2 MPa.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In the third embodiment described above, the estimated brake pressure immediately after a slip has occurred on any of the wheels is estimated in step S2 of the flowchart of FIG. 7, and the target brake pressure is determined based on the estimated brake pressure in step S22. Although the map is searched, in the fourth embodiment, the vehicle deceleration estimating means M
5 'estimates the vehicle deceleration as a time differential value of the vehicle speed Vv in step S2, and calculates the vehicle deceleration in step S22 in FIG.
The target brake pressure PB is searched by applying to the map of FIG.

Since the deceleration of the vehicle body immediately after the occurrence of the slip on the wheels can be considered to be substantially equal to the actual brake pressure at that time (that is, the estimated brake pressure in the third embodiment), according to the fourth embodiment. Also, the same function and effect as those of the third embodiment can be achieved.

Next, a fifth embodiment of the present invention will be described with reference to FIG.

Since the ABS control means M6 detects the slip of the wheel and controls the braking force to suppress the locking of the wheel, if the output of the ABS control means M6 is used, the slip state of the wheel is determined. While accurately grasping,
It is possible to calculate the target brake pressure PB that can exert the maximum braking force while suppressing the wheel slip.

Steps S1 to S5 of the fifth embodiment
Is the same as that of the first embodiment described above. If there is a possibility of contact in step S3, and if the ABS control means M6 for suppressing the locking of the wheels is not operating in step S31, that is, if the wheels are not slipping, the target brake pressure PB for automatic braking is determined in step S32. Is the initial value P
The automatic braking is executed by setting to 0. A in step S31
When the occurrence of slip is detected by operating the BS control means M6, a target brake pressure PB for automatic braking is calculated in step S33 based on the ABS target brake pressure of each wheel.
Specifically, when the ABS control means M6 calculates four ABS target brake pressures based on the slip ratio of each wheel,
Automatic braking is performed by adding a predetermined value dPabs (for example, 2 MPa) to the minimum ABS target brake pressure corresponding to the wheel having the largest slip ratio as the target brake pressure PB. However, it is assumed that the target brake pressure PB does not exceed the initial value P0.

Therefore, the slipping wheel generates only the braking force corresponding to the ABS target brake pressure smaller by the predetermined value dPabs than the target brake pressure PB, and the non-slip wheel corresponds to the target brake pressure PB itself. Even if a braking force is generated, the difference in braking force between the two wheels is suppressed to the maximum value corresponding to the predetermined value dPabs = 2 MPa. This makes it possible to stabilize the vehicle behavior when a slip occurs due to the automatic braking.

Next, a sixth embodiment of the present invention will be described with reference to FIG.

The sixth embodiment also uses the output of the ABS control means M6.
This is the same as that of the first embodiment described above. Step S3
, The ABS control state of the left front wheel WFL and the right front wheel WFR are the same in steps S41 and S42, that is, the ABS control of both the left front wheel WFL and the right front wheel WFR, or the ABS control of both If not, in step S43, the target brake pressure PB
Is set to P2.

On the other hand, in steps S41 and S42, the left front wheel W
When the ABS control states of the FL and the right front wheel WFR are different, that is, when the right front wheel WFR is ABS-controlled in step S41 and the left front wheel WFL is not ABS-controlled, or in step S42, the left front wheel WFL is not ABS-controlled and the right front wheel WFR is not ABS-controlled. If ABS is controlled, step S
At 43, the target brake pressure PB is set to P3 smaller than P2.
Set to.

As described above, when the ABS control states of the left and right front wheels WFL and WFR are different, that is, the left and right front wheels WF
When the slip ratios of L and WFR are different, the target brake pressure PB for automatic braking is set to P2 when the slip ratios are equal.
By setting P3 smaller than the left and right front wheels W
The difference in the braking force between FL and WFR can be reduced to stabilize the vehicle behavior.

Next, a seventh embodiment of the present invention will be described with reference to FIG.

The seventh embodiment also uses the output of the ABS control means M6.
This is the same as that of the first embodiment described above. Step S6
When the automatic braking is executed for the first time in step S7,
And the target brake pressure PB is an initial value P0 (for example, 6
(MPa) and automatic braking is started. When the occurrence of slip is detected by the operation of the ABS control device M6 in step S51 of the next loop, the target brake pressure for automatic braking is calculated in step S52 based on the ABS target brake pressure of each wheel as follows. I do. That is, the ABS control means M6 controls the four ABSs based on the slip ratio of each wheel.
When the target brake pressure is calculated, a predetermined value dPa is set to the minimum ABS target brake pressure corresponding to the wheel having the largest slip ratio.
bs (for example, 2 MPa) is added, and the automatic braking is executed as the target brake pressure PB. However, it is assumed that the target brake pressure PB does not exceed the initial value P0.

If the ABS control means M6 is not operated in step S51, it can be considered that the braking force of the wheels is substantially proportional to the slip ratio. Can be. Therefore, in step S53, the difference between the slip ratios of the left and right front wheels WFL, WFR (or the left and right rear wheels WRL, WRR) is λ2 (for example,
2%) or more and the difference in braking force between the left and right wheels is large, the target brake pressure PB is reduced by dP in step S54. In step S55, the left and right front wheels WFL, W
When the difference in the slip ratio between the FRs (or the left and right rear wheels WRL, WRR) is less than λ1 (eg, 1%) and the difference between the braking forces on the left and right wheels is small, the target brake pressure PB is increased by dP in step S56. Press. Step S5
If the difference between the slip ratios is between λ1 and λ2 in S55, the target brake pressure PB is set to the initial value P in step S57.
Hold at 0.

As described above, when the ABS control means M6 is operating, the predetermined value dPabs is added to the minimum ABS target brake pressure corresponding to the wheel with the largest slip ratio, and the target brake pressure PB is automatically set as the target brake pressure PB. Since the braking is performed, the slipping wheel generates only the braking force corresponding to the ABS target brake pressure smaller by the predetermined value dPabs than the target brake pressure PB, and the non-slip wheel generates the target brake pressure PB itself. Even when the corresponding braking force is generated, the braking force difference between the two wheels is set to the predetermined value d at the maximum value.
Pabs = 2 MPa, and the vehicle behavior can be stabilized when a slip occurs due to automatic braking.

When the difference between the left and right wheels is large when the ABS control means M6 is not operating, the target brake pressure PB for automatic braking is reduced, and when the difference between the left and right wheels is small, the automatic braking is reduced. Since the braking target brake pressure PB is increased, the maximum braking force for avoiding contact can be secured while preventing the vehicle behavior from becoming unstable due to the difference between the left and right braking forces.

The embodiments of the present invention have been described above. However, various design changes can be made in the present invention without departing from the gist thereof.

For example, the brake pressures P0, P1, dPab
Specific numerical values such as s are not limited to the numerical values of the embodiment.

[0063]

As described above, according to the first aspect of the present invention, when a slip is detected by the slip detecting means during braking by the braking control means, the braking force correction means sets the target braking force of the braking control means. Is reduced, the slip of the wheels can be suppressed, and the braking force difference between the left and right wheels can be reduced to prevent the vehicle behavior from becoming unstable.

According to the second aspect of the present invention,
Since the target braking force is corrected so that the slip amount detected based on the rotation speed of the wheel is equal to or less than a predetermined value, the slip of the wheel is accurately suppressed to effectively reduce the difference in the braking force between the left and right wheels. Can be.

According to the third aspect of the present invention,
Since the actual braking force when the wheel slips is estimated, and the target braking force is corrected based on the estimated braking force,
By controlling the magnitude of the braking force to an optimal value according to the slip state of the wheel, the slip of the wheel can be suppressed, and the difference in braking force between the left and right wheels can be effectively reduced.

According to the fourth aspect of the present invention,
Since the vehicle deceleration when the wheel slips is estimated, and the target braking force is corrected based on the estimated vehicle deceleration, the magnitude of the braking force is controlled to an optimum value according to the wheel slip state. It is possible to suppress wheel slip and effectively reduce the difference in braking force between the left and right wheels.

According to the invention described in claim 5,
Since the target braking force is corrected based on the braking force by the ABS control means, it is possible to reduce the difference in braking force between the left and right wheels while suppressing the slip of the wheels more accurately.

According to the invention described in claim 6,
Since the target braking force is reduced when the difference in braking force between the left and right wheels is detected, the difference in braking force can be accurately reduced.

According to the invention described in claim 7,
When a difference in braking force between the left and right wheels is detected, the target braking force is reduced based on the difference in braking force, so that the difference in braking force can be reduced more accurately.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving safety device.

FIG. 2 is a block diagram of a braking system.

FIG. 3 is a block diagram showing a circuit configuration of an electronic control unit.

FIG. 4 is a flowchart for explaining the operation of the first embodiment;

FIG. 5 is a map for searching for the possibility of contact based on relative speed and relative distance.

FIG. 6 is a flowchart for explaining the operation of the second embodiment.

FIG. 7 is a flowchart for explaining the operation of the third embodiment and the fourth embodiment;

FIG. 8 is a graph illustrating the estimation of the brake pressure immediately after the occurrence of a slip;

FIG. 9 is a map for searching a target brake pressure from an estimated brake pressure.

FIG. 10 is a map for searching a target brake pressure from a vehicle deceleration.

FIG. 11 is a flowchart for explaining the operation of the fifth embodiment;

FIG. 12 is a flowchart illustrating the operation of the sixth embodiment.

FIG. 13 is a flowchart illustrating the operation of the seventh embodiment.

[Explanation of symbols]

 M1 Contact possibility estimating means M2 Braking control device M3 Slip detecting means M4 Braking force correcting means M5 Braking force estimating means M5 'Body deceleration estimating means M6 ABS control means WFL Left front wheel (wheel) WFR Right front wheel (wheel) WRL Left rear Wheel (wheel) WRR Right rear wheel (wheel) PB Target brake pressure (target braking force) Sa Radar device (object detection means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B60T 8/58 ZYW B60T 8/58 ZYWZ G01S 13/93 G01S 13/93 Z G08G 1/16 G08G 1/16 C (72 ) Inventor Kenji Odaka 1-4-1, Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) LL16 5J070 AC02 AC06 AD01 AE01 AE20 AF03 BF11

Claims (7)

[Claims] 1. An object detecting means (Sa) for detecting an object in a traveling direction of the own vehicle, and a contact possibility estimating means for estimating a possibility that the own vehicle comes into contact with an object detected by the object detecting means (Sa). (M1)
And a braking control means (M2) for automatically operating the braking device when the possibility of contact is estimated by the contact possibility estimating means (M1). (WFL, WFR, WRL, WRR) detecting slip (M3), and braking control means (M2) when the slip detecting means (M3) detects a slip during braking by the braking control means (M2). ), A braking force correcting means (M4) for reducing the target braking force (PB). 2. The vehicle according to claim 1, wherein the slip detecting means (M3) includes a wheel (WF).
L, WFR, WRL, WRR) to detect slip based on the rotational speed of the vehicle. The braking force correcting means (M4) controls the slip amount of the wheels (WFL, WFR, WRL, WRR) to be equal to or less than a predetermined value. The driving safety device for a vehicle according to claim 1, wherein the target braking force (PB) is corrected. 3. A braking force estimating means (M5) for estimating an actual braking force at the time of braking by a braking control means (M2),
Based on the braking force estimated by the braking force estimating means (M5) when the slip detecting means (M3) detects a slip,
The driving safety device for a vehicle according to claim 1 or 2, wherein the braking force correcting means (M4) corrects the target braking force (PB). 4. A vehicle deceleration estimating means (M5 ') for estimating a vehicle deceleration during braking by a braking control means (M2), and a vehicle deceleration estimating when a slip detecting means (M3) detects a slip. 3. The vehicle according to claim 1, wherein the braking force correcting means (M4) corrects the target braking force (PB) based on the vehicle deceleration estimated by the means (M5 '). Driving safety device. 5. Wheels (WFL, WFR, WRL, WR)
ABS control means (M6) for preventing rotation lock of R)
When the ABS control means (M6) is activated during braking by the braking control means (M2), the braking force correcting means (M
4) correcting the target braking force (PB) of the braking control means (M2) based on the braking force by the ABS control means (M6). A driving safety device for a vehicle according to the above. 6. When a difference in braking force between the left and right wheels (WFL, WFR, WRL, WRR) is detected during braking by the braking control means (M2), the braking force correction means (M4) controls the braking control means (M2). The driving safety device for a vehicle according to any one of claims 1 to 5, wherein the target braking force (PB) is reduced. 7. When a braking force difference between the left and right wheels (WFL, WFR, WRL, WRR) is detected during braking by the braking control means (M2), the braking force correcting means (M4) is based on the detected braking force difference. The traveling safety device for a vehicle according to any one of claims 1 to 6, wherein the target braking force (PB) of the braking control means (M2) is corrected by using the control device.